The present invention relates generally to telecommunication networks, and more particularly, to a system and method for providing a high-speed, high capacity communication channel supporting a wide range of services.
In the modern telecommunication industry, improved technologies for transmitting information through an efficient medium are always needed. Technologies for fast data transmission keep evolving at a rapid pace. For the wired world, modems are still one of the key instruments for users to exchange information in a computer network. However, modems in general suffer from numerous performance degradations. For example, current dial-up modems are limited to a speed of about 56 kb/s using data compression technology. Moreover, in order not to sacrifice the accuracy of the information being transmitted, a Forward Error Correction Code (FECC) technique must be implemented to embed sufficient redundant information in the transmitted data, which inevitably reduces the overall data bandwidth.
For an Asymmetric Digital Subscriber Line (ADSL) modem, the current technology provides a transmission speed about 1.5 Mb/s for up stream data flow, and up to 9 Mb/s for down stream data flow. It may be noted that ADSL technology can support simultaneous voice and data exchange over a same phone line where a user can make a plain old phone service (POTS) call while simultaneously accessing a computer network through the ADSL technology.
Although ADSL technology offers high-speed data communications over standard phone lines and achieves bandwidth efficiency, it is at the expense of using a complex data compression technology such as Trellis Coded Modulation. The complexity of such coding technology inevitably increases packet loss rate, and thus in turn damages the integrity of the data transmitted.
The real potential of modem technology lies in the opportunities driven by multimedia applications required by today""s computer network users, quality and reliability performance, and the cost of such technology. More importantly, a winning technology is needed to support a range of services on a single platform, having scalability to suit different groups of users, and providing end-to-end error free services for mission critical applications.
Hence, the existing ADSL technology is thus not the ideal solution for low cost high speed information communication with multiple classes of services.
In the present invention, a system and method for providing a high-speed, high capacity communication channel supporting a wide range of services is disclosed. In one embodiment of the present invention, the system contains a set of multiple access nodes connected to both a transmitting end and a receiving end providing services to multiple users simultaneously operating on data, audio, video or multimedia communications. The system on the transmitting end includes an encoding modem whereby an encoding process is done. An incoming information stream is first divided into parallel first level sub streams based on their classes. For example, audio, video and data information are separated into three sub streams, and each of them is further divided into multiple second level sub streams. A set of unique orthogonal short-codes assigned to a given class is provided according to a predetermined code plan for encoding the information. The encoded information is then modulated by a bank of modulators, and thereafter, combined and transmitted through a shared wired communication channel such as a cable or optical fiber.
The system also has a multiple access node connected to one or more users or subscribers. The multiple access node manages to allow different users to share a single communication link and the same set of orthogonal codes by implementing a Code Sense Multiple Access Protocol. Using this protocol, each user can monitor available orthogonal codes at any given instant, and thus maximizes the use of the full set of the orthogonal code chosen by the code plan.
At the receiving end, the system may also include a decoding modem that can easily decode information encoded and transmitted by the encoding modem.